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THE PERIPHERAL NERVOUS SYSTEM
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ORGANIZATION OF THE NERVOUS SYSTEM
BRAINSPINAL CORD
CENTRALNERVOUSSYSTEM (CNS)
PERIPHERALNERVOUS SYSTEM
AFFERENT
NERVES
EFFERENT
NERVES
EXTERO-RECEPTORS
INTERO-RECEPTORS
SOMATIC AUTONOMIC
EFFECTORORGANS
SKELETALMUSCLES
SMOOTH AND CARDIAC MUSCLES AND GLANDS
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NEOCORTEX
THALAMUS
LIMBICCORTEX
BRAINSTEM
SPINALCORD
NOSE
EYE
TONGUE
EAR
SKIN
SMELL
VISION
TASTE
AUDITION
SOMATIC
SENSORY INFORMATION TRAVELSTO THE BRAIN VIA SPECIALIZED PATHWAYS
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SENSORY MODALITIES AND RECEPTOR CELLS
MODE RECEPTOR ORGANWARMTH NERVE ENDINGS SKINCOLD NERVE ENDINGS SKINPAIN NAKEDNERVE
ENDINGSSKIN
JOINTMOVEMENT &POSITION
NERVE ENDINGS VARIOUS
MUSCLELENGTH
NERVE ENDINGS MUSCLESPINDLE
MUSCLETENSION
NERVE ENDINGS GOLGI TENDONORGAN
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GRADED VS ALL OR NONE
• A RECEPTOR’S RESPONSE TO A STIMULUS IS GRADED
• IF THRESHOLD IS EXCEEDED, THE ACTION POTENTIAL RESULTING IS ALL OR NONE
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SENSORY MODALITIES AND RECEPTOR CELLS
MODE RECEPTOR ORGANVISION RODS,CONES EYEHEARING HAIR CELLS EARMOTION HAIR CELLS VESTIBULAR
APPARATUS
SMELL OLIFACTORYNEURONS
OLIFACTORYMUCOUS MEMB.
TASTE TASTE RECEPTORCELLS TASTE BUDS
TOUCH-PRESSURE
NERVE ENDINGS SKIN
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SENSORY TRANSDUCTION
ADEQUATE STIMULUS
MEMBRANECONDUCTANCE
CHANGE
GENERATORPOTENTIAL
ACTIONPOTENTIAL
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LOCALIZATION, DISTRIBUTION, AND ACUITY
• CODING OF LOCATION DEPENDS ON RECEPTOR LOCATION
• AREA COVERED BY RECEPTORS IN A SENSORY UNIT IS A RECEPTIVE FIELD
• ACUITY DEPENDS ON THE DENSITY OF RECEPTORS
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SLOW PAIN
• OCCURS AFTER A SECOND OR MORE
• OFTEN ASSOCIATED WITH TISSUE DESTRUCTION
• SUBJECTIVELY DESCRIBED AS BURNING, ACHING,THROBBING, NAUSEOUS, OR CHRONIC
• C FIBERS WHICH SYNAPSE IN THE SUBSTANTIA GELITANOSA
• FINAL PROJECTION IS THE FRONTAL CORTEX
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MECHANICAL, CHEMICAL AND THERMAL PAIN
• FAST PAIN IS GENERALLY MECHANICAL OR THERMAL
• SLOW PAIN CAN BE ALL THREE• CHEMICAL PAIN RECEPTORS:
BRADYKININ, SEROTONIN, HISTAMINE, POTASSIUM IONS, ACIDS, ACETYL CHOLINE AND PROTEOLYTIC ENZYMES
• PROSTAGLANDINS ENHANCE PAIN SENSATION
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BRAIN STRUCTURES AND PAIN
• COMPLETE REMOVAL OF THE SENSORY CORTEX DOES NOT DESTROY THE ABILITY TO PERCIEVE PAIN
• STIMULATION OF THE SENSORY CORTEX EVOKES A SENSATION OF PAIN
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PAIN CONTROL (ANALGESIA)
• THE ANALGESIA SYSTEM
• THE BRAIN’S OPIATE SYSTEM
• INHIBITION OF PAIN BY TACTILE STIMULATION
• TREATMENT OF PAIN BY ELECTRICAL STIMULATION
• REFERED PAIN
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THE ANALGESIA SYSTEM
• PREAQUEDUCTAL GRAY
• RAPHE MAGNUS NUCLEUS
• PAIN INHIBITORY COMPLEX IN DORSAL HORNS
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PAIN INHIBITORY COMPLEX: PRESYNAPTIC INHIBITION
PAINRECEPTOR
BRAIN STEM.NEURON
INHIBITORY NEURON
ANTEROLATERALPATHWAY
DORSAL HORN OFSPINAL CORD
+
-
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PAIN TRANSMISSION AND INHIBITION
• SUBSTANCE P IS THE NEUROTRANSMITTER: BUILDS UP SLOWLY IN THE JUNCTION AND IS SLOWLY DESTROYED
• PRESYNAPTIC INHIBITION BY INHIBITORY NEURON BLOCKS THE RELEASE OF SUBSTANCE P (ENKEPHALIN)
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THE BRAIN’S OPIATE SYSTEM
• OPIATE RECEPTORS EXIST IN MANY CENTERS OF THE BRAIN, ESPECIALLY IN THE ANALGESIA SYSTEM
• AMONG THE NATURAL SUBSTANCES WHICH ACTIVATE THESE RECEPTORS ARE: ENDORPHINS, ENKEPHALINS, AND MORPHINE
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INHIBITION OF PAIN BY TACTILE STIMULATION
• STIMULATION OF LARGE SENSORY FIBERS FOR TACTILE SENSATION INHIBITS PAIN TRANSMISSION FOR SAME REGION
• RUBBING OFTEN EASES PAIN
• LINAMENTS, OIL OF CLOVE, ETC.
• POSSIBLE EXPLANATION FOR ACUPUNCTURE?
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TREATMENT OF PAIN BY ELECTRICAL STIMULATION
• STIMULATION OF LARGE SENSORY NERVES
• ELECTRODES IN SKIN OR SPINAL IMPLANTS
• INTRALAMINAR NUCLEUS OF THALAMUS
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REFERED PAIN
• VISCERAL PAIN FIBERS SYNAPSE ON SAME SECONDARY NEURONS AS RECEIVE PAIN FIBERS FROM SKIN
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THE VISUAL SYSTEM
D. C. MIKULECKYPROFESSOR OF PHYSIOLOGY
ANDFACULTY MENTORING PROGRAM
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THE VISUAL SYSTEM SENSES ELEECTROMAGNETIC RADIATION
• ELECTROMAGNETIC RADIATION (EMR) SPANS THE ELECTROMAGNETIC SPECTRUM (EMS)
• FROM RADIO WAVES (VERY LONG) TO -RADIATION (VERY SHORT)
• VISIBLE LIGHT IS A SMALL PORTION OF THE SPECTRUM
• PHOTONS OF LIGHT INTERACT WITH MATTER
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ANATOMICAL ORGANIZATION
• THE EYE• CORNEA AND LENS: BEND LIGHT RAYS
AND FOCUS THEM ON THE RETINA• CILLIARY MUSCLES LOSSEN OR TIGHTEN
TO ADJUST LENS THICKNESS• RETINA: SITE OF PHOTORECEPTORS• FOVEA: MOST SENSITVE PART OF RETINA
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TEAR DUCTANDDRAINAGECANAL
PUPIL IRISSCLERA
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OPTIC DISC
OPTIC NERVE
BLOOD VESSELS
FOVEA
SCLERA
RETINA
CHOROID
VITREOUS HUMOR
AQUEOUS HUMOR
CORNEA
LENS
PUPIL
IRIS
CONJUNCTIVACILIARY BODY
SUSPENSORY LIGAMENTEXTERNAL EYEMUSCLE
STRUCTURE OF THE EYE
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THE PHOTORECEPTORS• RODS:
CYLLINDRICALLY SHAPED- BROAD RANGE OF WAVELENGTHS, NIGHT
• CONES: CONICALLY SHAPED-NARROW WAVELENGTH RANGE, COLOR
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BEFORE A PHOTON ARRIVES
•RHODOPSIN ABSORBS PHOTON AND CHANGES SHAPE
•A SEQUENCE OF BIOCHEMICAL STEPS
•MEMBRANE HYPERPOLARIZED
AFTER A PHOTON ARRIVES
MEMBRANE POLARIZED NORMALLY
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PATHWAYS FOR VISUAL INFORMATION
• OPTIC NERVE (GANGLION CELLS FROM RETINA)
• LEAVES THROUGH “BLIND SPOT”
• LATERAL GENICULATE NUCLEUS: PROJECTS TO CORTEX
• PRIMARY VISUAL CORTEX
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VISUAL ORIENTATION COLUMNS
• CELLS IN VARIOUS COLUMNS OF CORTEX RESPOND TO DIFFERENT ORIENTATIONS
• THESE DEVELOP DURING THE EARLY VISUAL EXPERIENCES OF YOUNG ANIMALS
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COLOR VISION
• TRICHROMATIC: RED, BLUE, GREEN
• PARVOCELLULAR NEURONS CARRY INFORMATION
• DIFFERENT CELL TYPES
• COLOR CONTRAST
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THREE KINDS OF CONES
• RED, BLUE, AND GREEN
• CONNECT TO SMALL GANGLION CELLS
• TRANSMIT COLOR INFORMATION TO PARVOCELLULAR NEURONS IN LGN
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COLOR NEURONS
• BROAD BAND: SINGLE COLOR, + INSIDE, - OUT
• SINGLE - OPPONENT: EXITED BY ONE COLOR IN CENTER, INHIBITED WHEN ANOTHER COLOR IN PERIPHERY
• DOUBLE OPPONENT: OPPOSING COLORS IN BOTH CENTER AND PERIPHERY
• ANNULAR FIELDS OVERLAP TO RECTANGULAR IN CORTEX
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LENS DEFECTS
• FOCUSING IN FRONT OF RETINA
• NEARSIGHTEDNESS (MYOPIA)
• USUALLY DUE TO WEAK CILIARY MUSCLES
• FOCUSING BEHIND THE RETINA
• FARSIGHTEDNESS(HYPEROPIA)
• LENS TOO STIFF (AGING)
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NEARSIGHTEDNESS (MYOPIA)
UNCORRECTED
CORRECTED
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FARSIGHTEDNESS (HYPEROPIA)
UNCORRECTED
CORRECTED
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VISUAL FIELD DEFECTS
• OPTIC NERVE:VISUAL FIELD ON SAME SIDE
• OPTIC CHIASM:OUTER HALF OF BOTH VISUAL FIELDS
• OPTIC TRACT: OPPOSITE HALF IN BOTH VISUAL FIELDS
• OPTIC RADIATIONS:LOWER OR UPPER QUADRANT ON OPPOSITE SIDE
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THE AUDITORY SYSTEM AND THE CHEMICAL SENSES
D. C. MIKULECKYPROFESSOR OF PHYSIOLOGY
ANDFACULTY MENTORING PROGRAM
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THE NATURE OF SOUND
• COMPRESSION AND RARIFICATION OF AIR
• WAVES OF HIGH AND LOW PRESSURE
• TRANSMIT MECHANICAL FORCES
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CHARACTERISTICS OF A PRESSURE WAVE
A
T = WAVELENGTH
A = AMPLITUDE
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ANATOMY OF THE EAR
• OUTER EAR
• MIDDLE EAR
• INNER EAR
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OUTER EAR
• ACTS TO FOCUS SOUND WAVES ON THE TYMPANIC MEMBRANE
• SHAPED LIKE A SOUND CONE
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OUTER EAR
PINNA
CANAL
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MIDDLE EAR
• THREE BONES LINK TYMPANIC MEMBRANE TO OVAL WINDOW
• VIBRATIONS TRANSMITTED MECHANICALLY
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MIDDLE EAR
TYMPANICMEMBRANE
OVALWINDOW
BONES OFMIDDLE EAR COCHLEAR
FLUIDSOUNDWAVE IN EAR CANAL
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INNER EAR
• SITE OF TRANSDUCTION
• VIBRATION OF COCHLEAR FLUID CAUSES BASILAR MEMBRANE TO VIBRATE
• HAIR CELLS ARE DEFORMED
• AUDITORY NERVE BECOMES EXCITED AS HAIR CELLS DEPOLARIZE
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INNER EAR
OVALWINDOW
COCHLEA
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STRUCTURE OF THE COCHLEA
SCALA VESTIBULI
COCHLEAR DUCT
SCALATYPANI
OVALWINDOW
ROUND WINDOW www.freelivedoctor.com
STRUCTURE OF COCHLEAR DUCT
BASILAR MEMBRANE
TECTORIAL MEMBRANEORGAN OF CORTI
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TRANSDUCTION MECHANISM
BASILAR MEMBRANE…..VIBRATES
TECTORIAL MEMBRANE STATIONARY
STEROCILIA
AUDITORY NERVE
HAIRCELLS
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TRANSDUCTION MECHANISM
TECTORIAL MEMBRANE STATIONARY
BASILAR MEMBRANE…..VIBRATES
STEROCILIABEND
AUDITORY NERVE HAIR
CELLS
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FREQUENCY DISCRIMINATION: LOCALIZATION OF DISPLACEMENT OF
BASILAR MEMBRANEBASE APEX
HIGH
LOW
MID
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AUDITORY PATHWAYS
COCHLEA
VENTRALCOCHLEARNUCLEUS MIDLINE
VENTRALCOCHLEARNUCLEUS
SUPERIOROLIVE
INFERIOR
COLLICULUS
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AUDITORY PATHWAYS (CONT.)
MIDLINE
SUPERIOROLIVE
INFERIOR COLLICULUS
INFERIOR COLLICULUS
MEDIAL GENICULATE
MEDIAL GENICULATE
TEMPORALCORTEX
TEMPORALCORTEX
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CHARACTERISTICS OF A PRESSURE WAVE
A
T = WAVELENGTH
A = AMPLITUDE
f = 1/T FREQUENCY www.freelivedoctor.com
PROPERTIES OF AUDITORY NERVE CELLS
• EACH AUDITORY NERVE FIBER HAS AN OPTIMUM FREQUENCY
• THIS TONOTOPIC ORGANIZATION ARISES FROM POSITION IN THE COCHLEA
• TONIC AND PHASIC NEURONS IN EACH AREA• SOME RESPOND TO CHANGE IN FREQUENCY• SOME RESPOND TO CHANGE IN AMPLITUDE
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SOUND LOCALIZATION
• INTERAURAL TIME DIFFERENCE
• TIME DELAY BETWEEN TWO EARS
• ALSO INTENSITY DIFFERENCES
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DISORDERS OF AUDITION
• LOSS OF HAIR CELLS: FREQUENCY SPECIFIC
• TINNITUS: RINGING
• CONDUCTIVE:l DAMAGE TO MIDDLE EAR
• CENTRAL: BRAIN TUMORS AND LESIONS
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THE VESTIBULAR APPARATUS
• SEMICIRCULAR CANALS: HAIR CELLS SENSE MOTION
• THREE COORDINATE PLANES: SUPERIOR, INFERIOR, AND HORIZONTAL
• UTRICLE AND SACCULE DETECT LINEAR ACCELERATION IN HORIZONTAL AND VERTICLE PLANES
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THE VESTIBULAR APPARATUS: UTRICLE & SACCULUS
ONE CANAL IN EACHCOORDINATEPLANE
AMPULLAUTRICLE&SACCULUS
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THE UTRICLE & SACCULUS
HAIR CELLSNERVE
CELLS
OTOLITHICMEMBRANE-GELATINOUSLAYER
OTOCONIA(CALCIUMCARBONATECRYSTALS)
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THE UTRICLE & SACCULUS
HAIR CELLSNERVE
CELLS
OTOLITHICMEMBRANE-GELATINOUSLAYER
OTOCONIA(CALCIUMCARBONATECRYSTALS)
HEAD MOVEMENT
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THE VESTIBULAR APPARATUS: SEMICIRCULAR CANALS
ONE CANAL IN EACHCOORDINATEPLANE
AMPULLAUTRICLE&SACCULUS
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THE AMPULLA
HAIR CELLSNERVE
CELLS
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THE AMPULLA
HAIR CELLSBENT
NERVECELLSFIRE
INERTIAL FLUID MOVEMENT
MOVEMENT OF HEAD
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TASTE SENSATION
• GUSTATORY RECEPTORS
• GUSTATORY PATHWAYS
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GUSTATORY RECEPTORS
• TASTE BUDS ON TONGUE LOCALIZED
• SWEET: TIP
• BITTER:BACK
• SOUR SIDES
• SALT: FRONT
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GUSTATORY PATHWAYS
• VII, IX, X CRANIAL NERVES
• TO GUSTATORY NUCLEUS IN BRAIN STEM
• VPM NUCLEUS OF THALAMUS
• GUSTATORY AREA OF NEOCORTEX
• VIA LIMBIC SYSTEM TO HYPOTHALAMUS
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THE OLIFACTORY SYSTEM
• RECEPTOR CELLS IN OLIFACTORY MUCOSAL MEMBRANE
• AXONS CROSS CRIBIFORM PLATE AND TERMINATE ON MITRAL CELLS IN OLIFACTORY BULB-FORM OLIFACTORY TRACT
• OLIFACTORY TRACT GOES TO LIMBIC SYSTEM AND TO ORBITOFRONTAL CORTEX
• CLOSELY ASSOCIATED WITH EATING AND MATING BEHAVIOR
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THE AUTONOMIC NERVOUS SYSTEM
• TWO NEURON CHAINS
• SYMPATHETIC
• PARASYMATHETIC
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TWO NEURON CHAINS
SPINEEFFECTOR
ORGAN
PRESYNAPTICNEURON
POSTSYNAPTICNEURON
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SYMPATHETIC
• GANGLION NEAR SPINE
• SHORT PREGANGLIONIC NEURONS
• LONG POSTGANGLIONIC NEURONS
• FLIGHT OR FIGHT
• POSTGANGLIONIC NEURONS ARE ADRENERGIC
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PARASYMPATHETIC
• GANGLION NEAR EFFECTOR ORGAN
• LONG PREGANGLIONIC NEURONS
• SHORT POSTGANGLIONIC NEURONS
• “COUCH POTATO”
• POSTGANGLIONIC NEURONS ARE CHOLINERGIC
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EFFECTS OF ANSORGAN S PHEART + -BLOODVESSELS
CONSTRICT(MOSTORGANS)
DILATE (HEART
AND SKELETAL)
DILATE (PENISAND CLITORIS)
BRONCHIOLES DILATE CONSTRICT
PUPIL DILATE CONSTRICT
DIGESTION INHIBIT ENHANCE
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